I haven't read the Malorie Blackman novel which Dominic Cooke has adapted and directed for the RSC; and, for once, I was grateful for my innocence. I found myself caught up in the narrative twists of this absorbing political allegory which posits a society in which a white underclass, the Noughts, is pitted against a ruling black majority, the Crosses.

The role-reversal, especially in the first half, pays off handsomely. We watch the growing friendship, across the race and class divide, between 16-year-old Callum and 14-year-old Sephy, whose father happens to be deputy prime minister. And, as the relationship matures, each pays a heavy price. Sephy is tormented by her schoolmates for consorting with the "Blankers", as they are damningly known, "who smell funny and eat weird food". Callum discovers that his father and brother are part of a liberation militia whose aim is to commit terrorist acts on the opposing "Daggers".

All this is worked out with considerable skill and enlivening detail. The script also brings out the contradictions inherent in this kind of two-tier society: Callum's father is both delighted that his son has been accepted as a token Nought at a school for high-achieving Crosses and, at the same time, endorses overthrow of the system. And the story has all kinds of resonances: one thinks of apartheid South Africa, sectarian Northern Ireland and, when a supermarket bomb kills innocent victims, of events in our own backyard.

The tension slackened only when the story got closer to the obvious source of Romeo and Juliet: there is a moment here when Callum and Sephy's planned escape is aborted by a stroke of bad luck, exactly as in Shakespeare's tragedy. The play also depends too much on the idea of a unified black community: a myth lately subverted by dramatists such as Roy Williams and Kwame Kwei-Armah.

But my qualms were stilled by the visceral excitement of Cooke's production. Christopher Shutt's sound score is also full of ominously reverberant echoes which prepare us for the big explosion. And the acting is uniformly impressive.